PMID- 20441720 OWN - NLM STAT- MEDLINE DCOM- 20101217 LR - 20221207 IS - 1555-2101 (Electronic) IS - 0160-6689 (Linking) VI - 71 IP - 11 DP - 2010 Nov TI - Cytochrome P450 2D6 phenotype predicts antidepressant efficacy of venlafaxine: a secondary analysis of 4 studies in major depressive disorder. PG - 1482-7 LID - 10.4088/JCP.08m04773blu [doi] AB - INTRODUCTION: Venlafaxine, a serotonin-norepinephrine reuptake inhibitor antidepressant, is metabolized primarily by the cytochrome P450 2D6 enzyme into O-desmethylvenlafaxine (ODV). The ODV/venlafaxine ratio can be used to distinguish between extensive metabolizers (EMs) and poor metabolizers (PMs). OBJECTIVES: To determine the relative efficacy and tolerability of venlafaxine in EM vs PM patients with major depressive disorder (MDD). METHOD: Data from 4 double-blind, placebo-controlled studies of patients with MDD were pooled. Blood samples were analyzed for plasma concentrations of venlafaxine, ODV, total venlafaxine + ODV, and ODV/venlafaxine ratio. Patients were classified as EMs or PMs on the basis of ODV/venlafaxine ratios. Changes from baseline in depression scale scores were compared between EMs and PMs using t tests. Rates of response, remission, discontinuation, and adverse events (AEs) were compared for EMs and PMs using Fisher exact tests. RESULTS: Compared with PMs, EMs had significantly greater mean changes from baseline on 4 of 5 depression rating scales (all 4 comparisons, P